GEO bubbles are ridiculously powerful, especially debuff bubbles. In addition, GEO is adept at both nuking and stunning. And bubbles can't be dispelled or resisted. Reapplication is almost instant compared to what BRD and COR have to do.
I mean, I can't even fathom how people can't see this. And I'm not arguing for a nerf because you really can and should bring at least one GEO to anything you do. It's just that good.